Strengths and difficulties. The Strength and Difficulties Questionnaire (SDQ), self-reported or filled out by parents, contains 25 items which assess different aspects of adjustment among children and adolescents focusing on behavioral symptoms. The questionnaire is intended to be completed by parents (or teachers) for children aged 3-16. Adolescents aged 11-16 can fill out the questionnaire by themselves (Goodman, 1997). The participants are asked to relate to 25 positive and negative statements, and respond as to what degree each statement fits their children, on a Likert scale of 1 (not true) to 3 (certainly true). The questionnaire is made up of five main factors: emotional symptoms, behavioral problems, attentiveness and hyperactivity, relations with the peer group, and pro-social behavior.